Evaluation of factors affecting tack coat bond strength

2019 ◽  
Vol 46 (4) ◽  
pp. 270-277 ◽  
Author(s):  
Moein Biglari ◽  
Seyed Mohammad Asgharzadeh ◽  
Saleh Sharif Tehrani
Keyword(s):  
Bonding Strength ◽  
Asphalt Mixture ◽  
Crumb Rubber ◽  
Application Rate ◽  
Concrete Pavements ◽  
Factors Affecting ◽  
Roller Compacted Concrete ◽  
Application Rates ◽  
Tack Coat ◽  
Optimum Application

Different types of distress occur in asphalt concrete pavements due to lack of bonding between existing old layer and overlay. Therefore, this paper evaluates the bonding strength between sand asphalt mixture as overlay and roller compacted concrete (RCC) as the existing layer. Four types of tack coat including crumb rubber modified (CRM), grade 60/70 binder, cationic slow-setting (CSS), and cationic rapid-setting (CRS) emulsion were considered, with 200, 400, and 600 g/m2 dosages. Different RCC surface temperatures including 0, 25, and 60 °C were chosen to evaluate the effect of ambient temperature on the bonding strength. Results showed that CRM and 60/70 binders have higher bonding strength in comparison to emulsions. The bonding strength at 0 °C for all types of tack coat was significantly lower than other temperatures. The optimum application rates of 200 g/m2 and 400 g/m2 were selected for the CSS and CRS emulsified binders respectively. The optimum application rate for the 60/70 and CRM binders was selected as 600 g/m2.

scholarly journals Influence of Ageing on Flexible Pavement Interface Bond under Repeated Shear Stresses

2020 ◽  
Vol 2 (2) ◽  
pp. 462-475
Author(s):  
Saad Issa Sarsam ◽  
Samah Abdulrazzaq AL Nuaimi
Keyword(s):  
Shear Strength ◽  
Permanent Deformation ◽  
Research Work ◽  
Application Rate ◽  
Shear Stresses ◽  
Interface Shear ◽  
Concrete Core ◽  
Application Rates ◽  
Tack Coat ◽  
Interface Bond

The durability of interface bond was not sufficiently taken into consideration, and the research work in this field is scares and scattered. The interface bond usually practices dynamic shear stresses throughout its service life while ageing due to volatilization provide stiffness at the interface. In this investigation, an attempt has been made to assess the durability of the interface bond in terms of resistance to ageing under repeated shear stresses. Two types of tack coat (Rapid Curing cutback RC-70 and Cationic Medium setting emulsion CMS) and three application rates have been implemented in the preparation of two layers slab samples (base overlaid by binder, and binder overlaid by wearing) courses using roller compactor. Asphalt concrete core specimens were obtained from the roller compacted slab samples and subjected to long term ageing, then the specimens were subjected to 1200 repeated shear stress cycles. The accumulation of permanent deformation was monitored. Afterwards, the specimens were tested for interface shear strength at 20 °C. Control specimens were also tested for comparison. It was concluded that ageing reduces the total microstrain for RC-70 tack coat by (43.6, 25.6, and 29.5) % and (50, 51.3, and 30.2) % for (binder-base) and (wearing-binder) interfaces for the application rate of (0.15, 0.33, 0.5) l/m2  respectively. However, ageing reduces the total microstrain for CMS tack coat by (37, 35.5, and 40.3) % and (45.2 , 49, and 46.8) % for (binder-base) and (wearing-binder) interfaces for the application rate of (0.1, 0.23, 0.35) l/m2  respectively. Ageing increases the interface bond shear strength by a range of (8-27)% for various interfaces, tack coat type and application rates.

scholarly journals Applying Wollastonite to Soil to Adjust pH and Suppress Powdery Mildew on Pumpkin

2019 ◽  
Vol 29 (6) ◽  
pp. 811-820
Author(s):  
Yuan Li ◽  
Arend-Jan Both ◽  
Christian A. Wyenandt ◽  
Edward F. Durner ◽  
Joseph R. Heckman
Keyword(s):  
Powdery Mildew ◽  
Soil Ph ◽  
Application Rate ◽  
Erysiphe Cichoracearum ◽  
Application Rates ◽  
Level Increase ◽  
Essential Nutrient ◽  
Optimum Application ◽  
Cucurbit Powdery Mildew ◽  
Plant Susceptibility

Although not considered an essential nutrient, silicon (Si) can be beneficial to plants. Si accumulator species such as pumpkin (Cucurbita pepo var. pepo) can absorb Si from soil. Si uptake may reduce plant susceptibility to fungal diseases such as cucurbit powdery mildew (Podosphaera xanthii and Erysiphe cichoracearum). We previously reported that wollastonite, an Organic Materials Reviews Institute–approved natural mineral, can increase soil Si level, increase soil pH, provide pumpkin plants with Si, and increase their resistance to powdery mildew. In this study, we examined the optimum application rate of wollastonite for pumpkins grown in pots and exposed to cucurbit powdery mildew. We confirmed that wollastonite has liming capabilities similar to regular limestone. Regardless of the application rates, wollastonite and limestone showed similar effects on soil chemistry and plant mineral composition. Pumpkin plants grown with the lower doses of wollastonite amendments (3.13 and 6.25 tons/acre) had the greatest tissue Si concentrations and demonstrated the greatest disease resistance. We conclude that wollastonite is a useful material for organic cucurbit (Cucurbitaceae) growers who want to increase soil pH and improve plant resistance to powdery mildew at the same time. Applying wollastonite at rates beyond the amount required to achieve a desirable soil pH for pumpkin production did not further increase Si uptake, nor did it further suppress powdery mildew development.

Laboratory investigation of modified bitumen for interlayer in rigid–flexible composite pavement

2020 ◽  
pp. 089270572093914 ◽  
Author(s):  
Gholamali Shafabakhsh ◽  
Saeed Ahmadi
Keyword(s):  
Shear Strength ◽  
Hydrated Lime ◽  
Crumb Rubber ◽  
Modified Bitumen ◽  
Direct Shear Tests ◽  
Application Rates ◽  
Shear Fatigue ◽  
Tack Coat ◽  
Bonding Properties ◽  
And Performance

Adhesion of composite pavement plays a significant role in the durability and maintenance of this type of pavement. The present research aims to assess the bonding and fatigue performance of rigid–flexible composite pavements through laboratory testing at different tack coat application rates. Three types of modified bitumen, crumb rubber-modified bitumen containing hydrated lime (CR/HL), crumb rubber-modified bitumen containing natural zeolite (CR/NZ), and crumb rubber-modified bitumen (CRMB), were selected as the tack coat. Shear fatigue and direct shear tests were utilized to assess the bonding properties of tack coats. The study also examines the behavior of modified bitumen by examining its viscosity, rheological properties, and performance grade. The results show that CR/NZ exhibits better performance in rheological behavior and at various temperatures compared to CR/HL and CRMB. Also, depending on the type of tack coat, shear strength tests show a range of 0.6–0.9 l m−2 as the optimal tack coat dosage. Finally, based on the optimal tack coat, shear strength ratings for various bitumen types may be classified as CRMB < CR/HL < CR/NZ.

Evaluation of Shear Strength on Pavement Layers by Use Tack Materials

2011 ◽  
Vol 255-260 ◽  
pp. 3176-3179 ◽  
Author(s):  
Jia Chong Du
Keyword(s):  
Shear Strength ◽  
Analysis Of Variance ◽  
Application Rate ◽  
Test Results ◽  
Anova Test ◽  
Lower Shear ◽  
Maximum Value ◽  
Tack Coat ◽  
Higher Temperature ◽  
Optimum Application

Pavement bonding associates with shear strength which depends on different tack coat materials and temperature. The higher temperature has, the lower shear strength is; and increasing the application rate does not significantly improve the shear strength. The test results show that the shear strength decreases with an increase in temperatures has the maximum value at optimum application rate (OAR) and emulsion asphalt used has higher shear strength than that of cutback asphalt. The tack materials and temperature are significantly effective the shear strength, in accordance with the statistic of two-way analysis of variance (ANOVA) test.

Factors Affecting the Tracking Performance of Tack Coat Materials

2019 ◽  
Vol 2673 (3) ◽  
pp. 355-364
Author(s):  
Quan Lv ◽  
Hussain U. Bahia
Keyword(s):  
Rheological Properties ◽  
Application Rate ◽  
Curing Temperature ◽  
Tracking Performance ◽  
Water Evaporation ◽  
Tire Pressure ◽  
Factors Affecting ◽  
Tack Coat ◽  
Short Time ◽  
Wheel Tracking

One commonly encountered problem with tack coats is the pickup of the tack coat material by haul trucks after placement, which is called tracking. In this study, the bitumen bond strength (BBS) test and loaded wheel tracking test (LWTT) are used to evaluate the tracking performance of the tack coat emulsion considering simulating the tire pressure in the field. The effect of critical factors including humidity, curing temperature and time, and residue application rate and dilution rate on the tracking performance of different tack coats were investigated. Results show that the tracking performance of the tack coat is dependent somewhat on the curing rate of the emulsion, but more importantly on the rheological properties of the residue. It is found that for all emulsions tested, water evaporation or curing happens in a very short time, as the applied layer is very thin in tack coat applications. However, if the rheological properties are not stiff enough, tracking will continue even after completion of water evaporation. In addition, both the modified BBS test (AASHTO T361) and LWTT (ASTM D6372) revealed that a minimum threshold for the G*/sinδ of the residue exists above which the tack coat become trackless. This minimum value is associated with a given temperature depending on the rheological properties of the emulsion residue. In other words, there is an equi-stiffness temperature at which all emulsions become trackless. A range of G*/sinδ values of 10–18 kPa was identified as the threshold above which an emulsion residue could transform to trackless.

Factors Related to the Appearance of Transverse Bumps in Asphalt Overlays Placed over Crack Sealant

2017 ◽  
Vol 2630 (1) ◽  
pp. 128-133
Author(s):  
Scott Shuler
Keyword(s):  
Asphalt Mixture ◽  
Application Rate ◽  
Asphalt Pavements ◽  
Transverse Cracks ◽  
Water Intrusion ◽  
Asphalt Overlay ◽  
Bow Wave ◽  
Tack Coat ◽  
Asphalt Overlays ◽  
Pavement Foundation

Crack sealants often are used as a preservation tool in asphalt pavements. These sealants are placed in cracks to prevent water intrusion into the pavement foundation. Through the reduction of water intrusion, the strength of foundation layers is maintained, and acceptable pavement performance is extended. However, when a hot-mix asphalt overlay is placed on top of a pavement that contains crack sealants, a bump and additional transverse cracks sometimes occur in the new overlay asphalt. These bumps and sometimes transverse cracks are initiated during breakdown rolling and become progressively more severe on further compaction. This paper presents the results of a 5-year study designed to identify factors that related to the appearance of these bumps and consequent cracks. The results of the study indicated that vibratory breakdown rolling, pavement gradient, sealant geometry, tack coat application rate, and tack coat adhesivity were factors that contributed most to the occurrence of bumps and transverse cracks during asphalt overlay construction over crack sealants. Observations suggested that transverse bumps and consequent cracks occurred in proportion to the size of the bow wave of asphalt concrete present immediately in front of the breakdown roller. The increase in the bow-wave size depended on asphalt mixture properties, breakdown roller size, speed, vibration characteristics, and pavement gradient. Three pavement test sections also indicated that the tack coat application rate had an effect on reduction in the appearance of transverse bumps.

scholarly journals Influence of Surface Texture on Interface Bond Shear Strength of Asphalt Concrete

2020 ◽  
Vol 1 (3) ◽  
pp. 8-14
Author(s):  
Saad Issa Sarsam
Keyword(s):  
Shear Strength ◽  
Bond Strength ◽  
Surface Texture ◽  
Asphalt Concrete ◽  
Maximum Size ◽  
Application Rate ◽  
Application Rates ◽  
Tack Coat ◽  
Base Course ◽  
Interface Bond

The bonding strength provided by the tack coat between asphalt concrete layers at the interface is considered as an essential issue in the performance of the flexible pavement throughout its service life. However, the surface texture of the pavement surface exhibits another essential issue in the bond strength. In this investigation, three layers of asphalt concrete (base, binder and wearing) courses with (25, 19, and 12.5) mm of nominal maximum size of aggregates have been prepared using roller compactor. Rapid curing cutback RC-70 and cationic medium setting emulsion CMS have been implemented as tack coats with three application rates. The slab specimens were subjected to mean texture depth determination using sand patch method. Core specimens of 102 mm diameter were obtained from the prepared slab samples and subjected to interface bond strength test with the aid of a special manufactured mold. Test results were analyzed and compared. It was concluded that when RC-70 tack coat was implemented, asphalt concrete binder course laid on base course exhibited the highest shear strength of 1600 kPa at an application rate of 0.33 liter/m2 when compared to other application rates. Asphalt concrete wearing course laid on binder course exhibited the highest shear strength of 1515 kPa at an application rate of 0.15 liter/m2 when compared to other application rates. When CMS tack coat was implemented, asphalt concrete binder course laid on base course exhibited the highest shear strength of 1620 kPa at an application rate of 0.23 liter/m2 when compared to other application rates. Finally, the asphalt concrete wearing course laid on binder course exhibited the highest shear strength of 2272 kPa at an application rate of 0.23 liter/m2 when compared to other application rates.

scholarly journals Effect of different soil and weather conditions on efficacy, selectivity and dissipation of herbicides in sunflower

2020 ◽  
Vol 66 (No. 9) ◽  
pp. 468-476
Author(s):  
Miroslav Jursík ◽  
Martin Kočárek ◽  
Michaela Kolářová ◽  
Lukáš Tichý
Keyword(s):  
Cation Exchange Capacity ◽  
Chenopodium Album ◽  
Soil Layer ◽  
Weather Conditions ◽  
Growing Season ◽  
Application Rate ◽  
Exchange Capacity ◽  
Vertical Transport ◽  
Application Rates ◽  
High Precipitation

Six sunflower herbicides were tested at two application rates (1N and 2N) on three locations (with different soil types) within three years (2015–2017). Efficacy of the tested herbicides on Chenopodium album increased with an increasing cation exchange capacity (CEC) of the soil. Efficacy of pendimethalin was 95%, flurochloridone and aclonifen 94%, dimethenamid-P 72%, pethoxamid 49% and S-metolachlor 47%. All tested herbicides injured sunflower on sandy soil (Regosol) which had the lowest CEC, especially in wet conditions (phytotoxicity 27% after 1N application rate). The highest phytotoxicity was recorded after the application of dimethenamid-P (19% at 1N and 45% at 2N application rate). Main symptoms of phytotoxicity were leaf deformations and necroses and the damage of growing tips, which led to destruction of some plants. Aclonifen, pethoxamid and S-metolachlor at 1N did not injure sunflower on the soil with the highest CEC (Chernozem) in any of the experimental years. Persistence of tested herbicides was significantly longer in Fluvisol (medium CEC) compared to Regosol and Chernozem. Dimethenamid-P showed the shortest persistence in Regosol and Chernozem. The majority of herbicides was detected in the soil layer 0–5 cm in all tested soils. Vertical transport of herbicides in soil was affected by the herbicide used, soil type and weather conditions. The highest vertical transport was recorded for dimethenamid-P and pethoxamid (4, resp. 6% of applied rate) in Regosol in the growing season with high precipitation.  

scholarly journals Effects of two wood-based biochars on the fate of added fertilizer nitrogen—a 15N tracing study

2021 ◽  
Author(s):  
Subin Kalu ◽  
Gboyega Nathaniel Oyekoya ◽  
Per Ambus ◽  
Priit Tammeorg ◽  
Asko Simojoki ◽  
...  
Keyword(s):  
Plant Uptake ◽  
Plant Biomass ◽  
Application Rate ◽  
Control Treatment ◽  
Organic N ◽  
N Leaching ◽  
Soil N ◽  
Mineral N ◽  
Total N ◽  
Application Rates

AbstractA 15N tracing pot experiment was conducted using two types of wood-based biochars: a regular biochar and a Kon-Tiki-produced nutrient-enriched biochar, at two application rates (1% and 5% (w/w)), in addition to a fertilizer only and a control treatment. Ryegrass was sown in pots, all of which except controls received 15N-labelled fertilizer as either 15NH4NO3 or NH415NO3. We quantified the effect of biochar application on soil N2O emissions, as well as the fate of fertilizer-derived ammonium (NH4+) and nitrate (NO3−) in terms of their leaching from the soil, uptake into plant biomass, and recovery in the soil. We found that application of biochars reduced soil mineral N leaching and N2O emissions. Similarly, the higher biochar application rate of 5% significantly increased aboveground ryegrass biomass yield. However, no differences in N2O emissions and ryegrass biomass yields were observed between regular and nutrient-enriched biochar treatments, although mineral N leaching tended to be lower in the nutrient-enriched biochar treatment than in the regular biochar treatment. The 15N analysis revealed that biochar application increased the plant uptake of added nitrate, but reduced the plant uptake of added ammonium compared to the fertilizer only treatment. Thus, the uptake of total N derived from added NH4NO3 fertilizer was not affected by the biochar addition, and cannot explain the increase in plant biomass in biochar treatments. Instead, the increased plant biomass at the higher biochar application rate was attributed to the enhanced uptake of N derived from soil. This suggests that the interactions between biochar and native soil organic N may be important determinants of the availability of soil N to plant growth.

scholarly journals Evaluation of the Regional-Scale Optimal K Rate Based on Sustainable Apple Yield and High-Efficiency K Use in Loess Plateau and Bohai Bay of China: A Meta-Analysis

Agronomy ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1368
Author(s):  
Wenzheng Tang ◽  
Wene Wang ◽  
Dianyu Chen ◽  
Ningbo Cui ◽  
Haosheng Yang ◽  
...  
Keyword(s):  
Loess Plateau ◽  
High Efficiency ◽  
Meta Analysis ◽  
Regional Scale ◽  
Fertilizer Application ◽  
Application Rate ◽  
Bohai Bay ◽  
The Loess Plateau ◽  
Application Rates ◽  
Relationship Model

In order to meet the growing food demand of the global population and maintain sustainable soil fertility, there is an urgent need to optimize fertilizer application amount in agricultural production practices. Most of the existing studies on the optimal K rates for apple orchards were based on case studies and lack information on optimizing K-fertilizer management on a regional scale. Here, we used the method of combining meta-analysis with the K application rate-yield relationship model to quantify and summarize the optimal K rates of the Loess Plateau and Bohai Bay regions in China. We built a dataset based on 159 observations obtained from 18 peer-reviewed literature studies distributed in 15 different research sites and evaluated the regional-scale optimal K rates for apple production. The results showed that the linear plus platform model was more suitable for estimating the regional-scale optimal K rates, which were 208.33 and 176.61 kg K ha−1 for the Loess Plateau and Bohai Bay regions of China, respectively. Compared with high K application rates, the optimal K rates increased K use efficiency by 45.88–68.57%, with almost no yield losses. The optimal K rates also enhanced the yield by 6.30% compared with the low K application rates.

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